BPhO Computational Challenge · Task 4

Photoelectric Effect Lab

E_photon = hc/λ K_max = E_photon − φ

01

Experiment setup

Controls

Cathode metal2.28 eV Wavelength400 nm 160 nm · ultraviolet800 nm · infrared Light intensity55% Fewer photonsMore photons Retarding voltage0.00 V 0 V6 V

i

Try this: raise intensity, then wavelength. Intensity changes the current; wavelength changes each photon’s energy.

02

Vacuum photocell

Live experiment

Photoemission active

✓

Photoelectrons are reaching the anode

Photon energy exceeds the work function and the retarding voltage.

03

Calculated results

Live readings

Photon energy3.10eV

Work function, φ2.28eV

Maximum kinetic energy0.82eV

Threshold wavelength544nm

Stopping voltage0.82V

Relative current0.55I / I_max

Photon energy budget3.10 = 2.28 + 0.82 eV

Work functionElectron KE

Key observation

Increasing intensity sends more photons per second, increasing current without changing the energy of each electron.

Einstein photoelectric equation · Static browser simulation Values use E_photon ≈ 1239.84 / λ(nm) eV